This invention relates to electrical connector systems having mating portions which are brought together to provide a plurality of interengaging electrical contacts. Such systems are used to facilitate connection and disconnection of electronic components. They commonly are designed to be used in conjunction with a "box-and-tray" arrangement, or "racking" system, in which a modular electronic control or communication unit enclosed in a suitable container is mounted on, and supported by, a shelf, or rack, which is secured in place in the environment into which the modular electronic unit is to be inserted. For example, modern aircraft are supplied with such trays, which are normally retained in position on the aircraft, and which are adapted to receive and support boxes containing modular electronic units, such as radio communication units, aircraft instrumentation, and component control units, etc. When servicing is required, a given box is removed from the tray and replaced by another. The connection and disconnection of the box, in order to be quickly and efficiently accomplished, requires mating electrical connector sections, one mounted on the tray and wired to the permanent aircraft electrical and electronic systems, and the other mounted on the box and wired to the electrical and electronic systems contained in the box. Each mating connector section carries a number of electrical terminals adapted to engage corresponding electrical terminals on the other.
The density of the electrical connector contacts for use in electronic racking systems has increased over the years due to the increased requirements for signal and power connections to complex electronic modules or black boxes, such as computers, monitoring equipment, etc. This increased contact density requires large forces (insertion forces) to mate the connector shells of the conventional prior art connectors. At the same time, the large capital investment in aircraft, and also in ground based electronic racking systems, demands maximum operational utilization. Defective or faulty electronic modules must be easily removed and replaced by substitute modules. Large insertion forces often result in bent or broken contacts which require the replacement of one or both of the integrating connector terminals, and may require the replacement of an expensive electronic module.
Numerous efforts have been made to deal with the problem of excessive force needed to bring conventional connector mating sections into engagement. One proposed solution to this problem is low, or zero, insertion force electrical connectors. In such connectors the contact terminals are not in axial alignment with their corresponding terminals as the two connector mating portions are brought together by relative motion toward one another. Instead the opposing terminals are laterally spaced until the mating portions have been brought together; and thereafter, the set of terminals in one portion is moved laterally, or sideward, into engagement (and therefore, electrical contact) with the corresponding terminals in the other portion.
The low insertion force arrangement is designed to minimize the resistance to interengaging movement of the two connector mating sections which otherwise would result from the sum of all the terminal mating forces plus extra resistances caused by any misalignment problems in the connector system.
In the field of low insertion force connectors, Saul et al., U.S. Pat. No. 2,654,872 (1953) discloses a connector wherein the separate terminals can be physically brought into contact position under light pressure, and then the pressure substantially increased by virtue of a rotatable eccentric cam-shaft to insure good electrical conductivity. Bishop et al., U.S. Pat. No. 2,802,189 (1957) and Blackhall, U.S. Pat. No. 2,744,968 (1956) disclose multiple jack connections wherein cam levers force reed switches into contact after an initial non-contacting alignment.
Modifications of these structures have been provided in a large body of patent art, of which the following are cited as examples: Mishelevich et al., U.S. Pat. No. 3,145,067 (1964); Shlesinger, U.S. Pat. No. 3,217,284 (1955); Peterson, U.S. Pat. No. 3,315,212 (1967); Asick, U.S. Pat. No. 3,392,235 (1968); Feeser et al., U.S. Pat. No. 3,430,183 (1969); Brendlen, (U.S. Pat. No. 3,453,586 (1969); Frederick, U.S. Pat. No. 3,489,968 (1970); Lockhard et al., U.S. Pat. No. 3,539,970 (1970); Anhalt, U.S. Pat. No. 3,587,037 (1971); Anhalt, U.S. Pat. No. 3,594,698 (1971); Barker, U.S. Pat. No. 3,601,759 (1971); Hartley, U.S. Pat. No. 3,629,788 (1971); Walkup, U.S. Pat. No. 3,683,317 (1972); and Lightner, U.S. Pat. No. 3,848,222 (1974).
In addition, various arrangements have been proposed for making electrical contact between a printed circuit board and electrical connectors, such as Pferd, U.S. Pat. No. 3,188,598 (1965); Conrad et al., U.S. Pat. No. 3,478,301 (1969); and McIver et al., U.S. Pat. No. 3,555,488 (1971).
While low insertion force concepts are potentially very useful in solving the problems experienced with electrical connector systems, we believe that the low insertion force solution does not, of itself, provide a full answer to the needs of modern connector systems. Since one of the primary causes of difficulty is human error in handling the insertion and extraction of electronic modular units, we are interested in simplifying the connection and disconnection process so that difficulties and delays owing to mistakes in handling the equipment are minimized.
The prior art mating connector devices which incorporate low insertion force terminals require an additional action by the installer when a new modular unit is being mounted on the shelf, i.e., an action beyond that required by mating connector devices which incorporate pin-and-socket telescoping terminals. In the connectors using pin-and-socket terminals, the installer places the modular unit on the shelf, pushes it against the backing plate, and then secures the hold-down mechanism. In the low insertion force devices of the prior art, an additional step is required--the step of manually moving a cam or lever to bring the low insertion force terminals into contact position.